Extraction of oil from edible items, such as grains (including corn), seeds, nuts, and legumes is common. Often, the item is ground, cracked, milled or otherwise processed to increase its surface area. Oil is then extracted from the ground item using various methods. Other materials are also commonly extracted from other vegetative materials.
One common method for extracting corn oil from corn is by using ethanol. Prior to contact with the ethanol, the corn kernels are crushed, flaked, milled, or otherwise modified into smaller pieces than the whole kernel. Because the majority of the oil is found in the germ of the kernel, the germ is often separated from the rest of the kernel. Ethanol is passed over, through, and otherwise around the corn pieces, and the oil leaches from the corn into the ethanol, where it is carried away from the remaining corn solids. The oil is then recovered from the ethanol. This process, however, can be costly, due to the high amounts of energy needed to separate the ethanol from the solids.
The recovery of oils from materials used in the fermentation process is desirable. Efforts have been made for the recovery of oils from seed germ prior to fermentation. For example, see Cao et al., Enzymatic Hydrolysis of Corn Starch After Extraction of Corn Oil with Ethanol, Applied Biochemistry and Biotechnology, Vol. 57/58, pages 39-47, 1996, and Hojilla-Evangelist et al., Sequential Extraction Processing of Flaked Whole Corn: Alternative Corn Fractionation Technology for Ethanol Production, Cereal Chemistry, 1992.